Numerical and experimental investigation of tsunamis generated by iceberg calving
With climate change as an increasingly important issue, the Greenland and Antarctic ice sheets have suffered rapid ice mass losses contributing to sea level rise. Iceberg calving is one of the main factors for ice mass loss and may also generate large tsunamis when icebergs calve into a water body,...
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | English |
| Published: |
2021
|
| Subjects: | |
| Online Access: | http://eprints.nottingham.ac.uk/64363/ https://eprints.nottingham.ac.uk/64363/1/thesis_FC.pdf |
| Summary: | With climate change as an increasingly important issue, the Greenland and Antarctic ice sheets have suffered rapid ice mass losses contributing to sea level rise. Iceberg calving is one of the main factors for ice mass loss and may also generate large tsunamis when icebergs calve into a water body, threatening the fishing and shipping industries and coastal communities. One of the most impressive tsunamis generated by iceberg calving with an amplitude of 45 to 50 m was observed at the Eqip Sermia glacier in Greenland in 2014. Herein, such tsunamis are called iceberg-tsunamis (IBTs). This study aims to investigate the generation and propagation of large IBTs. A novel numerical model is developed based on the Immersed Boundary Method (IBM) provided in a toolbox in the open source code Foam-extend 4.0. A new multiphase flow solver is implemented to solve the Reynolds-Averaged Navier-Stokes equations with the support of handling moving immersed boundaries, and it is then coupled with a motion solver to simulate Fluid-Structure Interaction (FSI) to determine the iceberg motion. Further, unique large-scale laboratory experiments were conducted in a 50 m $times$ 50 m large basin. Two rigid blocks with densities of $approx$920 kg/m$^3$ weighting up to 187 kg were used to mimic icebergs and to model the five idealised calving mechanisms: (A) capsizing, (B) gravity-dominated fall, (C) buoyancy-dominated fall, (D) gravity-dominated overturning and (E) buoyancy-dominated overturning. The analytical solution of a floating heaving sphere case is used to validate the newly implemented flow solver and the numerical radiated wave amplitudes show a maximum deviation of only 10.3% from the corresponding analytical solution. Further, the numerical model is used to simulate the two laboratory experiments from mechanisms B and D generating the largest and most dangerous IBTs. A laminar flow model is selected as the consideration of turbulence does not improve the accuracy. For IBT generation, the maximum vertical displacement in the ... |
|---|